U.S. patent number 6,981,855 [Application Number 10/259,308] was granted by the patent office on 2006-01-03 for drilling rig having a compact compressor/pump assembly.
This patent grant is currently assigned to Sandvik AB. Invention is credited to Jarmo Leppanen.
United States Patent |
6,981,855 |
Leppanen |
January 3, 2006 |
Drilling rig having a compact compressor/pump assembly
Abstract
A mobile drilling rig includes a platform mounted on drivable
ground supports. Drilling equipment is disposed on the platform and
is operated by a power system that includes hydraulic pumps, a
screw type air compressor, and a motor for driving the pumps and
the compressor. A gearbox is common to the hydraulic pumps and the
air compressor and includes an intermeshing gear arrangement for
transmitting an inputted power from the motor to the pumps and the
compressor. Compressed air from the compressor travels to an air
reservoir in which compressor oil is separated from the air. The
compressor oil is conducted to an oil inlet of the gearbox and is
circulated through the gearbox to an oil outlet of the gearbox
which communicates with an air inlet of the compressor.
Inventors: |
Leppanen; Jarmo (Gainesville,
FL) |
Assignee: |
Sandvik AB (Sandviken,
SE)
|
Family
ID: |
32029478 |
Appl.
No.: |
10/259,308 |
Filed: |
September 30, 2002 |
Prior Publication Data
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|
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Document
Identifier |
Publication Date |
|
US 20040060717 A1 |
Apr 1, 2004 |
|
Current U.S.
Class: |
418/201.1;
418/199; 417/199.1 |
Current CPC
Class: |
F04C
18/16 (20130101); F01C 11/00 (20130101); F04C
29/005 (20130101); F04C 29/02 (20130101); F16H
37/065 (20130101); E21B 7/02 (20130101); F01C
13/00 (20130101); F04C 29/0085 (20130101) |
Current International
Class: |
F01C
11/00 (20060101) |
Field of
Search: |
;173/28,43,26
;418/199,201.1 ;417/199.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gerrity; Stephen F.
Assistant Examiner: Lopez; Michelle
Attorney, Agent or Firm: Drinker Biddle & Reath LLP
Claims
What is claimed is:
1. An apparatus comprising: a hydraulic pump for pumping hydraulic
fluid for power transmission; an air compressor lubricated by
compressor oil; a gearbox common to the hydraulic pump and the air
compressor and including an intermeshing gear arrangement for
transmitting an inputted power to the hydraulic pump and the air
compressor, the intermeshing gear arrangement comprising an input
gear, a compressor drive gear, and a pump drive gear, the
compressor drive gear and the pump drive gear being operatively
connected with the input gear within the gearbox; and a source of
the compressor oil; the gearbox including an oil inlet connected to
the source of compressor oil, and an oil outlet, the oil inlet
being at a higher pressure than the oil outlet, wherein compressor
oil is circulated through the gearbox while inputted power is being
transmitted to the gear arrangement.
2. The apparatus according to claim 1 further including a motor
having a power output operably connected to the input gear of the
gear arrangement for driving the hydraulic pump and the air
compressor, the gearbox being coupled to a housing of the
motor.
3. The apparatus according to claim 2, wherein the oil outlet is
connected to a source of suction for sucking compressor oil out of
the gearbox.
4. The apparatus according to claim 3 wherein the source of suction
is an air inlet of the compressor.
5. The apparatus according to claim 4, further including an air
reservoir coupled to an air outlet of the air compressor for
receiving compressed air therefrom and for separating-out the
compressor oil, the oil inlet of the gearbox being connected to the
air reservoir for receiving compressor oil therefrom.
6. The apparatus according to claim 1 wherein said compressor drive
gear is connected to a drive shaft, and said pump drive gear meshes
with the compressor drive gear, the compressor drive gear and the
pump drive gear being rotatable about mutually parallel axes.
7. The apparatus according to claim 1 wherein the air compressor
comprises a screw compressor having a drive screw and a driven
screw arranged in intermeshing relationship, the drive screw being
joined to a drive shaft which is driven by said compressor drive
gear of the gear arrangement.
8. The apparatus according to claim 1 wherein the hydraulic pump
constitutes a first hydraulic pump, a second hydraulic pump being
disposed next to the first hydraulic pump and the air compressor
and being driven by the intermeshing gear arrangement in the
gearbox.
9. The apparatus according to claim 1 wherein the oil outlet is
connected to a source of suction for sucking compressor oil out of
the gearbox.
10. The apparatus according to claim 9 wherein the source of
suction is an air inlet of the compressor.
11. The apparatus according to claim 1, further including an air
reservoir coupled to an air outlet of the air compressor for
receiving compressed air therefrom and for separating-out the
compressor oil, the oil inlet of the gearbox being connected to the
air reservoir for conducting compressor oil therefrom to the
gearbox.
12. The apparatus according to claim 1, further including means for
supplying the compressor oil to the compressor independently of the
pump.
Description
BACKGROUND OF THE INVENTION
The present invention relates to mobile drilling rigs and, in
particular, to an arrangement of a motor, an air compressor and
hydraulic pumps on a mobile drilling rig.
A conventional mobile, steerable drilling rig 10, depicted in FIGS.
1 and 2, compresses a platform 12 below which a drivable ground
support is attached, such as a pair of rotatable wheels (not shown)
or two rotatable endless carrier tracks 14, disposed on respective
sides of the platform. An operator's cab 16 is disposed at a rear
end of the platform. Situated on the platform in front of the cab
16 is a drilling assembly 17 for drilling holes downwardly into the
ground. The drilling assembly 17 includes a swingable beam 18, such
as a mast whose lower end is pivotably connected to a fixed
pedestal 18a to be swingable about a horizontal axis extending
perpendicularly to a front-to-rear extending longitudinal axis A of
the rig. Thus, the mast 18 can be swung by hydraulic devices 21
from the vertical state depicted in FIG. 1 to a horizontal state
(not shown) in which the free end of the mast sits on a mast rest
20 disposed at a front end of the platform.
The mast is oriented horizontally when tramming, i.e., when driving
the rig from one site to another. On the other hand, the mast is
oriented vertically during a drilling operation. Mounted on the
mast is a hydraulically powered raising/lowering mechanism for
raising or lowering a drill string having a drill bit at its lower
end. The drill string is comprised of series of interconnected
drill rods that are stored in a carousel mounted on the mast.
Hydraulic devices such as motors or cylinders are provided for
rotating the carousel.
Hydraulic pumps 27 are provided (FIG. 3) for providing pressurized
fluid to the various hydraulic devices and hydraulic motors.
In order to flush cuttings from a hole as it is being drilled, it
is common to direct compressed air downwardly through the drill
string to the front face of the drill bit. The cuttings become
entrained in the airflow and are brought to the surface as the air
travels upwardly along the annulus surrounding the exterior of the
drill string. The compressed air also serves to cool the cutting
elements of the drill bit. The compressed air is produced by a
compressor, typically a screw compressor 22. The compressor
delivers compressed air to an air reservoir 19 (see FIG. 4) from
which it is conducted to the drill string. Lubricating oil is mixed
with the compressed air for lubricating the compressor. The
lubricating oil is separated from the compressed air within the
reservoir 19 and is conducted back to the compressor and the
compressor gear box 22a through a conduit 19a, as depicted in FIG.
4. The oil is propelled through the conduit 19a by a pressure
difference between the reservoir and the gearbox. The oil is then
sucked out of the gear box 22a and into the compressor inlet
through a conduit 19b.
In order to drive the screw compressor 22 and the hydraulic pumps
27, it is conventional to employ a motor 26, such as a fuel-driven
engine (e.g., a diesel engine) or an electric motor for example. In
a typical arrangement, the compressor 22 the motor 26, the motor
drive shafts, the pumps 27, and gearboxes for the compressor and
the pumps are laid out in a line extending parallel to the
longitudinal axis of the rig, as shown in FIGS. 2 and 3.
The gearing 23 on the compressor is disposed in a gearbox situated
between the rear fly wheel end of the motor and the compressor, as
shown in FIG. 3. A main gear 23a of the gearing is driven by the
motor and it, in turn, drives the compressor screws through
additional gears of the gearing 23.
Projecting in front of the engine is a first driveline 24 (see FIG.
3) which drives a first pump drive gearbox 24a of first hydraulic
pump assembly 24b which provides pressurized hydraulic fluid for
driving the tracks 14 (tramming). A second driveline 25 drives
second pump drive gearbox 25b of a second hydraulic pump mechanism
25a which provides pressurized fluid for carrying out the drilling
functions and driving the cooling system for cooling the diesel
engine 26, the compressor oil, and the hydraulic oil.
It will be appreciated that the location of the center of gravity
of the load supported by the carrier tracks 14 is defined by the
layout of the equipment disposed on the platform.
From the standpoint of the design and cost of the carrier tracks
14, it would be desirable for the center of gravity to be centered
above the carrier tracks, i.e., be located as closely as possible
to a midpoint between the front and rear axles of each track (as
the rig is viewed from the side, as in FIG. 1). In that way, each
axle would have to be designed to support only about one-half of
the load. If, instead, the center of gravity of the load were
closer to one of the axles, that axle would have to support more
than one-half of the load. Hence, the tracks would have to be
oversized for carrying a greater load which is more costly and may
result in rig stability problems when tramming. Also, track life is
shortened due to the uneven weight distribution. The severity of
those problems is dependent upon the distance by which the center
of gravity is offset from the midpoint.
On the other hand, from the standpoint of drilling efficiency, it
is preferred that the center of gravity be disposed as close to the
mast carrier as possible, in order to maximize the pull-down force
acting downwardly on the drill bit during a drilling operation.
Therefore, it will be appreciated that the location of the optimum
center of gravity of the load is a design compromise between the
above-discussed considerations. However, in current drilling rigs
there is little versatility in the selection of the optimum
location of the center of gravity when manufacturing the rig. That
is, as noted above, the motor 26, the screw compressor 22, the
hydraulic pump assemblies 24a, 25b, and the gearboxes therefor,
occupy such a large portion of the front-to-rear dimension of the
platform that there is little ability to adjust the center of
gravity.
It would be desirable, therefore, to provide a way of making the
design of a drilling rig more versatile from the standpoint of
determining the location of the center of gravity of the load
supported by the tracks 14.
The gearboxes 24a, 25a of the first and second pump assemblies 24b,
25b are flooded with a fixed quantity of relatively heavy
lubricating gear oil which can lead to power loss and difficult
start-ups in cold weather, and periodic servicing is required to
replace the oil. Pump drive gear boxes on the drill rigs are high
maintenance and cost items. Such shortcomings are not present in
connection with the compressor gearbox in which thin compressor
lubricating oil is continuously circulated therethrough via
conduits 23a, 23b (FIG. 3) for lubricating and cooling the gear
box, i.e., a so-called "dry" gearbox.
It would be desirable: to lubricate and cool the hydraulic pump
gearings in a manner which reduces the power losses, to ease the
difficult diesel engine start-ups, to eliminate the need for
replacing the lubricating oil in the pump drive gear boxes, to
eliminate expensive, complicated, high maintenance and cost items,
to simplify the overall power train design and construction, and to
reduce the size of the power unit comprised of the diesel engine,
the compressor, and the hydraulic pumps
SUMMARY OF THE INVENTION
The present invention relates to an apparatus which includes a
hydraulic pump, an air compressor lubricated by compressor oil, and
a gearbox common to the hydraulic pump and the air compressor and
including an intermeshing gear arrangement for transmitting an
inputted power to the hydraulic pump and the air compressor. The
gearbox includes an oil inlet connected to a source of the
compressor oil, and also includes an oil outlet. The oil inlet is
at a higher pressure than the oil outlet, wherein compressor oil is
circulated through the gearbox while inputted power is transmitted
to the gear arrangement.
Preferably, the oil outlet is connected to an inlet of the
compressor which provides suction for sucking compressor oil out of
the gearbox.
Preferably, the source of compressor oil is a reservoir which
receives compressed air from the compressor and separates
compressor oil therefrom.
The invention also pertains to a mobile drilling rig which includes
the above described apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
The objects and advantages of the invention will become apparent
from the following detailed description of a preferred embodiment
thereof in connection with the accompanying drawings in which like
numerals designate like elements and in which:
FIG. 1 is a side elevational view of a conventional drilling
rig.
FIG. 2 is a top plan view of a conventional drilling rig.
FIG. 3 is an exploded perspective view of a diesel motor, screw
compressor, hydraulic pump arrangement on a conventional drilling
rig.
FIG. 4 is a schematic diagram of the flow of air from a compressor
and lubrication oil to the compressor on a conventional drilling
rig.
FIG. 5 is a plan view of a drilling rig according to the present
invention.
FIG. 6 is an exploded perspective view of a motor, compressor, and
pump arrangement according to the present invention.
FIG. 7 is a top plan view of the motor, compressor, and pump
arrangement according to the present invention.
FIG. 8 is a schematic diagram similar to FIG. 4, pertaining to the
present invention.
DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Depicted in FIG. 5 is a drilling rig 30 on which the present
invention is employed. That drilling rig is basically similar to
that of FIG. 2 in terms of the overall equipment provided. That is,
the drilling rig 30 includes a platform 12 to which a drivable
ground support (e.g., tracks 14 or wheels) is attached. An
operator's cab 16 is disposed at a rear end of the platform.
Situated in front of the cab is a beam 18 whose lower end is
connected to a fixed pedestal 18a and is swingable about a
horizontal axis between a vertical state to a horizontal state in
which the free end of the beam sits on a rest 20 situated at the
front of the platform. The beam can be in the form of a mast which
carries a carousel in which drill rods are stored. The mast 18 is
swung by hydraulic devices 21 to an upright state during a drilling
operation and to a horizontal state for tramming to a new work
site. Mounted on the mast is a hydraulic mechanism for raising or
lowering drill rods and rotating the carousel. Pressurized
hydraulic fluid for actuating the hydraulic devices is provided by
hydraulic pumps 50, 52.
A conventional screw compressor 22 is provided for providing
compressed air to a drill bit in order to flush cuttings from a
hole being drilled. The screw compressor comprises a male (drive)
screw and a female (driven) screw arranged to mesh with the male
screw, as is conventional, e.g., see the conventional screw
compressor depicted in copending Ser. No. 10/147,883, filed May 20,
2002, which is incorporated by reference herein. The compressed air
from the screw compressor is stored in an air reservoir 19 (FIG. 8)
before being conducted to the drill string.
A motor 26 is provided for driving the screw compressor 22 and the
hydraulic pumps 50, 52. The motor 26 can be any suitable
conventional type such as an electric motor or a fuel-driven engine
(such as a diesel engine).
In accordance with the present invention, a more compact
arrangement of the motor 26, the compressor 22 and the pumps 50, 52
is provided, as well as a new pump drive lubrication technique.
Instead of providing separate gearboxes for the compressor and the
hydraulic pump as in the prior art, there is provided a single
gearbox 60. That gearbox includes an outer casing 61, having a
flange 63 that is bolted to a flywheel housing 65 of the motor and
forms an enclosed gear chamber. Each pump 50, 52 includes a flange
53 connected to the gearbox casing 61, and the compressor 22
includes a flange 55 connected to the casing 61.
A drive shaft 70 driven by the engine drives two coaxial drive
gears 72, 74 disposed in the gear chamber. A first of those gears
72 constitutes a compressor drive gear in that it drives a gear 76
connected to a first of the screws of the compressor 22; that
driver screw (male screw) then drives a second screw which meshes
with the first screw. Air is compressed between the meshing
screws.
The hydraulic pumps 50, 52 also include respective input shafts to
which are connected gears 78, 80 respectively. Those gears are
driven by the second drive gear 74, which constitutes a pump drive
gear. The gear ratio between the compressor drive gear 72 and the
compressor input gear 76 can be different than the gear ratio
between the pump drive gear 74 and the pump input gears 78, 80,
whereby the compressor can be driven at a different speed than the
pumps.
In order to lubricate the gears in the gearbox 60, an oil input
conduit 90 extends from the reservoir 19 to the gearbox 60 and the
compressor 22 for conducting lubricating oil into the gear chamber
and the compressor. The oil is conventional compressor oil that is
normally used in screw compressors and which is substantially less
viscous than gear oil that is normally used to lubricate the gears
of a pump. The compressor oil has a viscosity grade no greater than
about 1000 cSt at 30.degree. F., and preferably is 750 cSt at
30.degree. F. High pressure air, mixed with compressor oil, is
conducted from the compressor 22 to the air reservoir 19 which
separates the air from the oil. The separated compressor oil can be
conducted to the compressor and to the gear housing through the
conduit 90 due to a difference in pressure between the reservoir 19
and the gearbox 60. In the gearbox, the compressor oil, together
with some pressurized air, is injected toward the meshing zones of
the respective gears 72, 74, 76, 78, 80.
An oil output conduit 92 extends from the gear chamber to the
compressor inlet for conducting the oil/air from the gearbox to the
compressor inlet. Thus, a light stream of cool, fresh compressor
oil is continuously circulated through the gearbox 60, and is
sucked out of the gearbox by suction from the compressor or from a
separate pump. The gearbox can thus be called a "dry" gearbox.
Alternatively, if the compressor oil exiting the gearbox is not to
be delivered to the compressor air inlet, a separate suction pump
could be used to suck the oil out of the gearbox.
The pump gearing, as well as the compressor gearing is thereby
lubricated in a manner which minimizes power losses, facilitates
start-up and avoids the need for oil replacement, in contrast to
conventional pump drive gearboxes which are flooded with much
heavier gear oil, e.g., typically having a viscosity grade of about
20,000 cSt at 30.degree. F. Thus, by utilizing a gearbox that is
common to the compressor and the pumps, the advantageous
lubrication technique commonly employed in compressor gearboxes is
available to the pump gears as well.
If desired, the engine 26 can be provided with a disconnect such as
a clutch between the flywheel and the gearbox, to facilitate
starting of the engine in cold weather. It would also be possible
to provide the hydraulic pumps and/or the compressor with
respective clutches, but that is not preferred, in order to
minimize the number of parts and maximize the robustness of the
system.
It will also be appreciated that by utilizing a common gearbox for
compressor gears and pump gears, the length of the compressor/pump
assembly can be considerably shortened as compared to conventional
assemblies, thereby providing enhanced versatility in locating the
center of gravity of such an assembly along the longitudinal
dimension of the rig platform. That, in turn, provides greater
opportunity to optimize the location of the load on the ground
support by centering, or nearly centering that center of gravity
relative to the ground support tracks (or wheels).
Although the present invention has been described in connection
with preferred embodiments thereof, it will be appreciated by those
skilled in the art that additions, deletions, modifications, and
substitutions not specifically described may be made without
departing from the spirit and scope of the invention as defined in
the appended claims.
* * * * *